Optimized melting of compacted dri
Patent Information
- Application Number
- EP2023828735
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-04-25
- Filing Date
- 2023-12-13
- Publication Date
- 2025-10-29
AI Technical Summary
Compressed DRI, such as HBI and HCl, pose challenges during melting due to their reactivity and size limitations, leading to reduced productivity and increased energy requirements in existing melting processes.
Comminuting HBI and HCl before feeding them into the melting process to produce fragments of specific sizes, which can be fed to an electric arc furnace, submerged arc furnace, or other melting units, allowing for a higher addition rate without increasing energy output.
The comminution method reduces the time required to melt the fragments, enabling a higher addition rate and improving productivity while minimizing the disadvantages associated with melting uncompressed DRI.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Title of the invention
[0003] Optimized melting of densified DRI
[0004] field of technology
[0005] The application relates to a method for melting DRI consisting at least partially of HBI and / or HCl by means of a melting process.
[0006] State of the art
[0007] It is known to reduce iron oxide-containing materials by direct reduction with reducing gas in a reduction unit—for example, a fixed bed, a moving bed, or a fluidized bed—at elevated temperatures. The solid product of direct reduction is called sponge iron or DRI (direct reduced iron); it is very porous and therefore highly reactive, for example, with respect to oxidation. During further processing, DRI is usually melted.
[0008] To reduce reactivity and thus facilitate further processing, DRI is often compacted while hot – i.e., as HDRI (hot direct reduced iron), hot sponge iron, or hot direct reduced iron. The compaction product is called, for example, HBI (hot briquetted iron) in the production of briquettes, or HCl (hot compacted iron) in the case of DRI production in a fluidized bed. Especially for fine-particle HDRI dust, for example, from fluidized bed processes, compaction to HBI or HCl helps prevent yield losses due to dust loss and quality degradation.
[0009] The common size available worldwide, due to an apparent density greater than 5.0 g / cm 3The dimensions of shippable HBI briquettes are 106 x 48 x 33 mm; this results from the desire to achieve the highest possible HBI output with the fewest possible briquetting machines. The apparent density of HCl is lower than that of HBI—typically in the range of 3.5–4.2 g / cm 3 - and is therefore not suitable for shipping due to the IMO (International Maritime Organization). HCl can also be smaller than HBI, for example, 50 x 38 x 22 mm.
[0010] If densified DRI—such as HBI or HCl—is melted during further processing—for example, in an electric arc furnace, a melting unit, or a submerged arc furnace (SAF)—the range of the feed rate to a melting process is determined by the time required to melt a briquette. This also depends on the energy available for the melting process, which in turn can influence its productivity. Compared to melting DRI, HBI has disadvantages in this regard.
[0011] Summary of the invention
[0012] Technical task
[0013] A method is presented that allows to reduce or avoid at least some of the disadvantages mentioned above when using compacted DRI.
[0014] Technical solution
[0015] This object is achieved by a method for melting sponge iron DRI consisting at least partially of hot-briquetted sponge iron HBI and / or hot-compacted sponge iron HCl by means of a melting process, wherein the hot-briquetted sponge iron HBI and / or the hot-compacted sponge iron HCl is comminuted before being fed to the melting process, and fragments of the hot-briquetted sponge iron HBI or the hot-compacted sponge iron HCl obtained during the comminution are fed to the melting process.
[0016] As described above, DRI can be uncompressed or compressed. HBI and HCl are special cases of the general term DRI; they refer to compressed DRI.
[0017] The product of a compaction of DRI carried out at a temperature of the DRI to be briquetted above 650°C is called HBI hot briquetted iron if its apparent density is above 5.0 g / cm 3 For densified DRI that does not fully meet these criteria - i.e. an apparent density of less than or equal to 5.0 g / cm 3 and / or a temperature of the DRI to be briquetted of 650°C or less -, the term HCl hot compacted iron is common.
[0018] For the purposes of this application, HBI and HCl are defined as above. Information on HBI can be found, for example, in the HOT BRIQUETTED IRON (HBI) QUALITY ASSESSMENT GUIDE, the International Iron Metallics Association August 2018, and current International Maritime Organization I MO regulations.
[0019] The melting process is preferably carried out using electrical energy.
[0020] Advantageous effects of the invention
[0021] Comminution produces fragments that are smaller than the underlying HBI or HCl. Fragments require less time to melt. Accordingly, the process according to the invention allows for a higher addition rate to a melting process than if HBI or HCl were added without the comminution according to the invention. To increase the addition rate, it is no longer necessary to increase the energy input to the melting process, as was previously the case, which can have an adverse impact on productivity. Disadvantages compared to melting undensified DRI are thus at least reduced.
[0022] It is preferred if the comminution is a crushing process; this takes place in comminution machines such as crushers, and it preferably takes place in at least two stages.
[0023] A crushing process produces fragments as fragments of HBI or HCl.
[0024] A crushing process is carried out using crushers; a single crusher or a crushing system with multiple crushers can be used—for example, arranged in several consecutive stages, with a subsequent stage being supplied with the fragments or pieces produced in the previous stage as starting material for the comminution taking place there. A crushing process carried out using several consecutive stages is multi-stage.
[0025] A crushing process is used to reduce solid material to a smaller size; it is broken up into smaller pieces in crushing machines such as crushers using breaking processes.
[0026] The comminution is preferably carried out to a size of the fragments - also called grain size - which lies in a range from 3.35 mm to 31.5 mm, preferably from 3.35 mm to 25 mm, particularly preferably 6.3 mm to 16 mm. The limits of the ranges are also included. The upper limit for the size of the fragments preferably obtained during comminution is preferably 31.5 mm, particularly preferably 25 mm, very particularly preferably 16 mm. The lower limit for the size of the fragments preferably obtained during comminution is preferably 3.35 mm, particularly preferably 6.3 mm. This size has proven to be advantageous with regard to the effects during melting desired according to the invention.
[0027] The above grain sizes refer to US standard ASTM E11.
[0028] In the process of comminution to a grain size according to the above-mentioned range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges, in practice some smaller fragments and possibly also some larger fragments will be obtained.
[0029] According to one embodiment, fragments obtained during comminution are fed to the melting process, regardless of whether they actually lie within the above-mentioned range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges. Thus, not only fragments whose grain size lies within the above-mentioned range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges are fed to the melting process, but also fragments lying outside this range or the sub-ranges.
[0030] According to another embodiment, which will be explained in more detail below, a minimum size is defined for the fragments arising during comminution, and fragments arising during comminution below the minimum size are separated, and only fragments above the minimum size are fed to the melting process.
[0031] According to one embodiment, fragments obtained during comminution are only fed into the melting process if they actually lie in the above-mentioned range of 3.35 to 31.5 mm or its preferred and particularly preferred sub-ranges.
[0032] Preferably, the DRI consists entirely of HBI and / or HCl.
[0033] According to a preferred embodiment, the melting process comprises at least one member of the group of processes consisting of
[0034] Melting in an electric arc furnace EAF;
[0035] Melting in a submerged arc furnace SAF,
[0036] Melting in an open slag bath furnace OSBF, melting in a melting unit, melting in a converter vessel.
[0037] A melting unit melts at least partially based on electrical energy.
[0038] EAF, SAF and OSBF are not to be understood as a melting aggregate in the context of this application.
[0039] A converter vessel, for example, is understood to mean a steelworks converter for steel production. According to one embodiment, a minimum size is defined for the fragments generated during comminution, and fragments below the minimum size generated during comminution are separated.
[0040] The separation is carried out, for example, by sieving.
[0041] The fragments below the minimum size can be fed into a process for the production of HBI or HCl - for example by means of bucket elevators or pneumatic conveying to be compacted together with HDRI.
[0042] Fragments above the minimum size are at least partially fed into the melting process.
[0043] Short description of the drawings
[0044] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of embodiments, which are explained in more detail in conjunction with the schematic and exemplary drawings.
[0045] Fig. 1 schematically shows the implementation of an embodiment of the method according to the invention with HBI.
[0046] Fig. 2 schematically shows the implementation of an embodiment of the process according to the invention with HCl.
[0047] Description of the embodiments
[0048] Examples
[0049] Figure 1 shows how DRI 20 – in this case HDRI – produced in a reduction unit 10 based on direct reduction in a fixed bed or fluidized bed is compressed in a briquetting device 30 to form HBI 40. The HBI is fed – if necessary after transport to another location, for example by rail or ship – to a melting process in a melting device 50. The melting device is, for example, a device suitable for carrying out a member of the group of processes consisting of
[0050] Melting in an electric arc furnace EAF;
[0051] Melting in a submerged arc furnace SAF, melting in an open slag bath furnace OSBF,
[0052] Melting in a melting unit
[0053] Melting in a converter vessel.
[0054] Before feeding – which in the example shown takes place via an intermediate hopper 60; however, it can also take place directly, i.e., without an intermediate hopper – the HBI 40 is crushed in the comminution device 70. This can be single-stage or multi-stage, for example, two-stage. In the example shown, the comminution device is a crusher. Fragments of the HBI 40 obtained during comminution are fed to the melting device 50 via the intermediate hopper 60.
[0055] Figure 2 shows how DRI 90 – in this case HDRI – produced in a reduction unit 80 based on direct reduction in a fluidized bed or fluidized bed is compressed in a compacting device 100 to form HCl 110. The HCl 110 is then fed, optionally locally for compaction in a plant network, to a melting process in a melting device 120. The melting device is, for example, a device suitable for carrying out a member of the group of processes consisting of
[0056] Melting in an electric arc furnace EAF;
[0057] Melting in a submerged arc furnace SAF,
[0058] Melting in an open slag bath furnace OSBF, melting in a melting unit, melting in a converter vessel.
[0059] Before feeding – which in the example shown takes place via an intermediate hopper 130; however, it can also take place directly, i.e., without an intermediate hopper – the HCl 110 is crushed in the comminution device 140 – this can be single-stage or multi-stage, for example, two-stage. In the example shown, the comminution device is a crusher. Fragments 150a, 150b of the HCl 110 obtained during comminution are sieved in a screening device 160. Only the fragments 150a above a minimum size are fed to the melting device 120 via the intermediate hopper 130. The fragments 150b below the minimum size are fed to the compacting device 100 to be compacted there together with HDRI.
[0060] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. List of reference symbols
[0061] 10 Reduction unit
[0062] 20 DRI
[0063] 30 Briquetting device
[0064] 40 HBI
[0065] 50 melting device
[0066] 60 intermediate bunkers
[0067] 70 Shredding device
[0068] 80 Reduction unit
[0069] 90 DRI
[0070] 100 Compacting device
[0071] 110 HCl
[0072] 120 melting device
[0073] 130 intermediate bunkers
[0074] 140 Shredding device
[0075] 150a, 150b Fragments
[0076] 160 screening device
Claims
Claims 1. A method for melting sponge iron DRI (20, 90) consisting at least partially of hot-briquetted sponge iron HBI (40) and / or hot-compacted sponge iron HCl (110) by means of a melting process, wherein the hot-briquetted sponge iron HBI (40) and / or the hot-compacted sponge iron HCl (110) is comminuted before being fed to the melting process, and fragments of the hot-briquetted sponge iron HBI (40) or the hot-compacted sponge iron HCl (110) obtained during the comminution are fed to the melting process.
2. Method according to claim 1, characterized in that the comminution is a crushing process which preferably takes place in at least two stages.
3. Method according to claim 1 or 2, characterized in that the comminution takes place to a size of the fragments which lies in a range from 3.35 mm to 31.5 mm, preferably from 3.35 mm to 25 mm, particularly preferably 6.3 mm to 16 mm.
4. Process according to one of claims 1 to 3, characterized in that the DRI (20,90) consists entirely of HBI (40) and / or HCl (110).
5. Method according to one of claims 1 to 4, characterized in that the melting process comprises at least one member of the group of methods consisting of Melting in an electric arc furnace EAF; Melting in a submerged arc furnace SAF, Melting in an open slag bath furnace OSBF, melting in a melting unit, melting in a converter vessel.
6. Method according to one of claims 1 to 5, characterized in that a minimum size is defined for the fragments arising during comminution, and fragments arising during comminution below the minimum size are separated.